Dose counter for medicament inhaler

ABSTRACT

A new and improved inhaler includes an accurate and consistent mechanical dose metering system that dispenses dry powdered medicament in discrete amounts or doses for patient inhalation, a pressure relief system that manages pressure within a medicament reservoir of the inhaler to ensure consistently dispensed doses, and a dose counting system indicating the number of doses remaining in the inhaler.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to co-pending provisionalU.S. patent application serial No. 60/213,668, filed Jun. 23, 2000(entitled “Breath-Actuated Dry Powder Inhaler”), and co-pendingprovisional U.S. patent application serial No. 60/213,382, filed Jun.23, 2000 (entitled “De-Agglomerator for Breath-Actuated Dry PowderInhaler”). Each of these co-pending applications is assigned to theassignee of the present disclosure and incorporated herein by reference.

FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to an apparatus and method foradministering medicament for inhalation by a patient and, moreparticularly, to a dry powdered medicament inhaler.

BACKGROUND OF THE DISCLOSURE

[0003] Metered dose medicament inhalers are well known for dispensingmedicament to the lungs of a patient, for treating asthma for example.Existing types of medicament dispensing inhalers include pressurizedpropellant inhalers, aqueous solution inhalers, and dry-powderedinhalers.

[0004] U.S. Pat. No. 5,503,144 to Bacon, for example, shows a drypowdered inhaler. The inhaler includes a reservoir for containing a drypowdered medicament, a metering chamber for removal of the powderedmedicament from the reservoir in discrete amounts, and an air inlet forentraining the removed powdered medicament through a mouthpiece uponpatient inhalation.

[0005] Another example is U.S. Pat. No. 5,971,951 to Ruskewicz, whichshows an inhaler including a motor driven cam mechanism for extrudingaqueous medicament through a porous membrane to form a medicamentaerosol for inhalation by a patient. The inhaler also includes sensors,circuitry and a microprocessor that determines the rate of patientinhalation and operates the extrusion mechanism only upon adequateinhalation levels.

[0006] A pressurized propellant, or “aerosol” inhaler is shown in U.S.Pat. No. 5,447,150 to Bacon, which also discloses a simple, mechanicalactuation assembly for ensuring that medicament is dispensed from theinhaler only upon adequate inhalation by a patient. The actuationassembly works by applying a pre-load to a valve of the aerosolcontainer sufficient to cause a dose release, but prevents the releaseby applying a pneumatic resisting force. The dose of medicament is thenreleased upon a patient inhalation strong enough to move a door withinthe assembly, which in turn releases the pneumatic resisting force.

[0007] What is still desired, however, is a new and improved inhaler foradministering medicament for patient inhalation. Preferably, the new andimproved inhaler can be used with dry powdered medicament. In addition,the new and improved inhaler will preferably include mechanicalassemblies for metering doses of medicament, managing medicamentreservoir pressure, and counting the number of doses remaining in theinhaler.

SUMMARY OF THE DISCLOSURE

[0008] The present disclosure, therefore, provides a new and improvedmedicament inhaler having a unique dose metering system. The inhalerincludes a mouthpiece for patient inhalation, a delivery passageway fordirecting an inhalation induced air flow through the mouthpiece, achannel extending from the delivery passageway, and a reservoir forcontaining medicament, with the reservoir having a dispenser portconnected to the channel. In a preferred form, the dose metering systemincludes a cup received in the channel, which is movable between thedispenser port and the delivery passageway, a cup spring biasing the cuptowards one of the dispenser port and the passageway, and a yoke movablebetween at least two positions. The yoke includes a ratchet engaging thecup and preventing movement of the cup when the yoke is in one of thepositions, and allowing movement of the cup when the yoke is in anotherof the positions.

[0009] The present disclosure also provides a medicament inhaler havinga unique reservoir pressure system. The inhaler includes a sealedreservoir having a dispenser port, and a channel communicating with thedispenser port, and a cup assembly movably received in the channel. In apreferred form, the pressure system includes a pressure relief port inthe channel, and a conduit providing fluid communication between aninterior of the sealed reservoir and the pressure relief port of thechannel. The cup assembly includes a recess adapted to receivemedicament when aligned with the dispenser port, a first sealing surfaceadapted to seal the dispenser port when the recess is unaligned with thedispenser port, and a second sealing surface adapted to seal thepressure relief port when the recess is aligned with the dispenser portand unseal the pressure relief port when the recess is unaligned withthe dispenser port.

[0010] The present disclosure additionally provides a medicament inhalerhaving a unique dose counter. The inhaler includes a mouthpiece forpatient inhalation, a dose metering system including a pawl movablealong a predetermined path during the metering of a dose of medicamentto the mouthpiece by the dose metering system, and a dose counter. In apreferred form, the dose counter includes a bobbin, a rotatable spool,and a rolled ribbon received on the bobbin, rotatable about an axis ofthe bobbin. The ribbon has indicia thereon successively extendingbetween a first end of the ribbon secured to the spool and a second endof the ribbon positioned on the bobbin. The dose counter also includesteeth extending radially outwardly from the spool into the predeterminedpath of the pawl so that the spool is rotated by the pawl and the ribbonadvanced onto the spool during the metering of a dose to the mouthpiece.

[0011] Thus, the present disclosure provides a new and improved inhalerincluding a simple, accurate and consistent mechanical dose meteringsystem that dispenses dry powdered medicament in discrete amounts ordoses for patient inhalation, a reservoir pressure system that ensuresconsistently dispensed doses, and a dose counter indicating the numberof doses remaining in the inhaler.

[0012] Further features and advantages of the presently disclosedinhaler will become more readily apparent to those having ordinary skillin the art to which the present disclosure relates from the drawings andthe detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that those having ordinary skill in the art will more readilyunderstand how to construct a dry powdered medicament inhaler inaccordance with the present disclosure, a preferred embodiment isdescribed below with reference to the drawing figures wherein:

[0014]FIG. 1 is a first side isometric view of a dry powdered medicamentinhaler according to the present disclosure;

[0015]FIG. 2 is an exploded, second side isometric view of the inhalerof FIG. 1;

[0016]FIG. 3 is a second side isometric view of a main assembly of theinhaler of FIG. 1;

[0017]FIG. 4 is a second side isometric view of the main assembly of theinhaler of FIG. 1, shown with a yoke removed;

[0018]FIG. 5 is an exploded first side isometric view of the mainassembly of the inhaler of FIG. 1;

[0019]FIG. 6 is an exploded enlarged isometric view of a medicament cupof the inhaler of FIG. 1;

[0020]FIG. 7 is an exploded first side isometric view of a hopper and ade-agglomerator of the inhaler of FIG. 1;

[0021]FIG. 8 is an exploded second side isometric view of the hopper anda swirl chamber roof of the de-agglomerator of the inhaler of FIG. 1;

[0022]FIG. 9 is an exploded first side isometric view of a case, camsand a mouthpiece cover of the inhaler of FIG. 1;

[0023]FIG. 10 is an enlarged side isometric view of one of the cams ofthe inhaler of FIG.

[0024]FIG. 11 is a second side isometric view of the yoke of the inhalerof FIG. 1;

[0025]FIG. 12 is a first side isometric view of the yoke of the inhalerof FIG. 1, showing a ratchet and a push bar of the yoke;

[0026]FIG. 13 is a schematic illustration of lateral movement of a bossof the medicament cup in response to longitudinal movement of theratchet and the push bar of the yoke of the inhaler of FIG. 1;

[0027]FIG. 14 is an enlarged isometric view of a dose counter of theinhaler of FIG. 1;

[0028]FIG. 15 is an exploded enlarged isometric view of the dose counterof the inhaler of FIG. 1; and

[0029]FIG. 16 is an enlarged isometric view, partially in section, of aportion of the inhaler of FIG. 1 illustrating medicament inhalationthrough the inhaler.

[0030] Like reference characters designate identical or correspondingcomponents and units throughout the several views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Referring to FIGS. 1 through 16, the present disclosure providesa new and improved inhaler 10 for dispensing a dry-powdered medicamentin metered doses for patient inhalation. The inhaler 10 of the presentdisclosure provides many beneficial features including but not limitedto a dose metering system that dispenses dry powdered medicament indiscrete amounts or doses for patient inhalation, a medicament reservoirpressure system for managing pressure within the reservoir, and a dosecounting system indicating the number of doses remaining in the inhaler10.

[0032] The inhaler 10 generally includes a housing 18, and an assembly12 received in the housing (see FIG. 2). The housing 18 includes a case20 having an open end 22 and a mouthpiece 24 for patient inhalation, acap 26 secured to and closing the open end 22 of the case 20, and acover 28 pivotally mounted to the case 20 for covering the mouthpiece 24(see FIGS. 1, 2 and 9). The housing 18 is preferably manufactured from aplastic such as polypropylene, acetal or moulded polystyrene, but may bemanufactured from metal or another suitable material.

[0033] The internal assembly 12 includes a reservoir 14 for containingdry powered medicament in bulk form, a de-agglomerator 32 that breaksdown the medicament between a delivery passageway 34 and the mouthpiece24, and a spacer 38 connecting the reservoir to the de-agglomerator.

[0034] Reservoir

[0035] The reservoir 14 is generally made up of a collapsible bellows 40and a hopper 42 having an dispenser port 44 (see FIGS. 2-5 and 7-8) fordispensing medicament upon the bellows 40 being at least partiallycollapsed to reduce the internal volume of the reservoir. The hopper 42is for holding the dry powder medicament in bulk form and has an openend 46 closed by the flexible accordion-like bellows 40 in asubstantially air-tight manner. An air filter 48 covers the open end 46of the hopper 42 and prevents dry powder medicament from leaking fromthe hopper 42 (see FIG. 7).

[0036] Spacer

[0037] A base 50 of the hopper 42 is secured to a spacer 38, which is inturn secured to the de-agglomerator 32 (see FIGS. 3-5 and 7-8). Thehopper 42, the spacer 38, and the de-agglomerator 32 are preferablymanufactured from a plastic such as polypropylene, acetal or mouldedpolystyrene, but may be manufactured from metal or another suitablematerial. The hopper 42, the spacer 38 and the de-agglomerator 32 areconnected in a manner that provides an air tight seal between the parts.For this purpose heat or cold sealing, laser welding or ultrasonicwelding could be used, for example.

[0038] The spacer 38 and the hopper 42 together define the medicamentdelivery passageway 34, which preferably includes a venturi 36 (see FIG.16) for creating an entraining air flow. The spacer 38 defines a slidechannel 52 communicating with the dispenser port 44 of the hopper 42,and a chimney 54 providing fluid communication between the medicamentdelivery passageway 34 and a supply port 56 of the de-agglomerator 32(see FIGS. 7 and 8). The slide channel 52 extends generally normal withrespect to the axis “A” of the inhaler 10.

[0039] De-Agglomerator

[0040] As its name implies, the de-agglomerator 32 breaks downagglomerates of dry powder medicament before the dry powder leaves theinhaler 10 through the mouthpiece 24. The de-agglomerator includes aswirl chamber 58 extending from the supply port 56 to an outlet port 60connected to the mouthpiece 24 (see FIG. 16). The de-agglomerator 32also includes two diametrically opposed inlet ports 62 that extendsubstantially tangential to the circular cross-section of the swirlchamber. Radial vanes 64 are positioned at the top of the swirl chamberand are sized such that at least a portion of breath-actuated airstreams entering through the diametrically opposed inlet ports 62collide with the vanes.

[0041] The inhaler 10 preferably includes a de-agglomerator of the typedisclosed in co-pending provisional U.S. patent application serial No.60/213,382, filed Jun. 23, 2000 (entitled “De-Agglomerator forBreath-Actuated Dry Powder Inhaler 10”), which has been incorporatedherein by reference. It should be understood that although the inhaler10 of the present disclosure is shown with a particular de-agglomerator32, the inhaler 10 is not limited to use with the de-agglomerator shownand can be used with other types of de-agglomerators or a simple swirlchamber.

[0042] Dose Metering System

[0043] The dose metering system includes a first yoke 66 and a secondyoke 68 mounted on the internal assembly 12 within the housing 18, andmovable in a linear direction parallel with an axis “A” of the inhaler10 (see FIG. 2). An actuation spring 69 is positioned between the cap 26of the housing 18 and the first yoke 66 for biasing the yokes in a firstdirection towards the mouthpiece 24. In particular, the actuation spring69 biases the first yoke 66 against the bellows 40 and the second yoke68 against cams 70 mounted on the mouthpiece cover 28 (see FIG. 9).

[0044] The first yoke 66 includes an opening 72 that receives andretains a crown 74 of the bellows 40 such that the first yoke 66 pullsand expands the bellows 40 when moved towards the cap 26, i.e., againstthe actuation spring 69 (see FIG. 2). The second yoke 68 includes a belt76, which receives the first yoke 66, and two cam followers 78 extendingfrom the belt in a direction opposite the first yoke 66 (see FIGS. 3, 11and 12), towards the cams 70 of the mouthpiece cover 28.

[0045] The dose metering system also includes the two cams 70 mounted onthe mouthpiece cover 28 (see FIGS. 9 and 10), and movable with the cover28 between open and closed positions. The cams 70 each include anopening 80 for allowing outwardly extending hinges 82 of the case 20 topass therethrough and be received in first recesses 84 of the cover 28.The cams 70 also include bosses 86 extending outwardly and received insecond recesses 88 of the cover 28, such that the cover 28 pivots aboutthe hinges 82 and the cams 70 move with the cover 28 about the hinges.

[0046] Each cam 70 also includes first, second and third cam surfaces90, 92, 94, and the cam followers 78 of the second yoke 68 are biasedagainst the cam surfaces by the actuation spring 69. The cam surfaces90, 92, 94 are arranged such the cam followers 78 successively engagethe first cam surfaces 90 when the cover 28 is closed, the second camsurfaces 92 when the cover 28 is partially opened, and the third camsurfaces 94 when the cover 28 is fully opened. The first cam surfaces 90are spaced further from the hinges 82 than the second and the third camsurfaces, while the second cam surfaces 92 are spaced further from thehinges 82 than the third cam surfaces 94. The cams 70, therefore, allowthe yokes 66, 68 to be moved by the actuation spring 69 parallel withthe axis “A” of the inhaler 10 in the first direction (towards themouthpiece 24) through first, second and third positions as the cover 28is opened. The cams 70 also push the yokes 66, 68 in a second directionparallel with the axis “A” (against the actuation spring 69 and towardsthe cap 26 of the housing 18) through the third, the second and thefirst positions as the cover 28 is closed.

[0047] The dose metering system further includes a cup assembly 96movable between the dispenser port 44 of the reservoir 14 and thedelivery passageway 34. The cup assembly 96 includes a medicament cup 98mounted in a sled 100 slidably received in the slide channel 52 of thespacer 38 below the hopper 42 (see FIGS. 5 and 6). The medicament cup 98includes a recess 102 adapted to receive medicament from the dispenserport 44 of the reservoir 14 and sized to hold a predetermined dose ofdry powdered medicament when filled. The cup sled 100 is biased alongthe slide channel 52 from the dispenser port 44 of the hopper 42 towardsthe delivery passageway 34 by a cup spring 104, which is secured on thehopper 42 (see FIGS. 4 and 5).

[0048] The dose metering system also includes a ratchet 106 and a pushbar 108 on one of the cam followers 78 of the second yoke 68 that engagea boss 110 of the cup sled 100 (see FIGS. 5, 11 and 12). The ratchet 106is mounted on a flexible flap 112 and is shaped to allow the boss 110 ofthe sled 100 to depress and pass over the ratchet 106, when the boss 110is engaged by the push bar 108. Operation of the dose metering system isdiscussed below.

[0049] Reservoir Pressure System

[0050] The reservoir pressure system includes a pressure relief conduit114 in fluid communication with the interior of the reservoir 14 (seeFIGS. 7 and 8), and a pressure relief port 116 in a wall of the slidechannel 52 (see FIGS. 5 and 8) providing fluid communication with thepressure relief conduit 114 of the hopper 42.

[0051] The medicament cup assembly 96 includes a first sealing surface118 adapted to seal the dispenser port 44 upon the cup assembly beingmoved to the delivery passageway 34 (see FIGS. 5 and 6). A sealingspring 120 is provided between the sled 100 and the cup 98 for biasingthe medicament cup 98 against a bottom surface of the hopper 42 to sealthe dispenser port 44 of the reservoir 14. The cup 98 includes clips 122that allow the cup to be biased against the reservoir, yet retain thecup in the sled 100.

[0052] The sled 100 includes a second sealing surface 124 adapted toseal the pressure relief port 116 when the recess 102 of the cup 98 isaligned with the dispenser port 44, and an indentation 126 (see FIG. 6)adapted to unseal the pressure relief port 116 when the first sealingsurface 118 is aligned with the dispenser port 44. Operation of thepressure system is discussed below.

[0053] Dose Counting System

[0054] The dose counting system 16 is mounted to the hopper 42 andincludes a ribbon 128, having successive numbers or other suitableindicia printed thereon, in alignment with a transparent window 130provided in the housing 18 (see FIG. 2). The dose counting system 16includes a rotatable bobbin 132, an indexing spool 134 rotatable in asingle direction, and the ribbon 128 rolled and received on the bobbin132 and having a first end 127 secured to the spool 134, wherein theribbon 128 unrolls from the bobbin 132 so that the indicia issuccessively displayed as the spool 134 is rotated or advanced.

[0055] The spool 134 is arranged to rotate upon movement of the yokes66, 68 to effect delivery of a dose of medicament from the reservoir 14into the delivery passageway 34, such that the number on the ribbon 128is advanced to indicate that another dose has been dispensed by theinhaler 10. The ribbon 128 can be arranged such that the numbers, orother suitable indicia, increase or decrease upon rotation of the spool134. For example, the ribbon 128 can be arranged such that the numbers,or other suitable indicia, decrease upon rotation of the spool 134 toindicate the number of doses remaining in the inhaler 10. Alternatively,the ribbon 128 can be arranged such that the numbers, or other suitableindicia, increase upon rotation of the spool 134 to indicate the numberof doses dispensed by the inhaler 10.

[0056] The indexing spool 134 preferably includes radially extendingteeth 136, which are engaged by a pawl 138 extending from one of the camfollowers 78 (see FIGS. 3 and 11) of the second yoke 68 upon movement ofthe yoke to rotate, or advance, the indexing spool 134. Moreparticularly, the pawl 138 is shaped and arranged such that it engagesthe teeth 136 and advances the indexing spool 134 only upon themouthpiece 24 cover 28 being closed and the yokes 66, 68 moved backtowards the cap 26 of the housing 18.

[0057] The dose counting system 16 also includes a chassis 140 thatsecures the dose counting system to the hopper 42 and includes shafts142, 144 for receiving the bobbin 132 and the indexing spool 134. Thebobbin shaft 142 is preferably forked and includes radially nubs 146 forcreating a resilient resistance to rotation of the bobbin 132 on theshaft 142. A clutch spring 148 is received on the end of the indexingspool 134 and locked to the chassis 140 to allow rotation of the spool134 in only a single direction (counterclockwise as shown in FIG. 14).Operation of the dose counting system 16 is discussed below.

[0058] Operation

[0059]FIG. 13 illustrates the relative movements of the boss 110 of thecup sled 100, and the ratchet 106 and the push bar 108 of the secondyoke 68 as the mouthpiece cover 28 is opened and closed. In the firstposition of the yokes 66, 68 (wherein the cover 28 is closed and the camfollowers 78 are in contact with the first cam surfaces 90 of the cams70), the ratchet 106 prevents the cup spring 104 from moving the cupsled 100 to the delivery passageway 34. The dose metering system isarranged such that when the yokes are in the first position, the recess102 of the medicament cup 98 is directly aligned with the dispenser port44 of the reservoir 14 and the pressure relief port 116 of the spacer 38is sealed by the second sealing surface 124 of the cup sled 100.

[0060] Upon the cover 28 being partially opened such that the second camsurfaces 92 of the cams 70 engage the cam followers 78, the actuatorspring 69 is allowed to move the yokes 66, 68 linearly towards themouthpiece 24 to the second position and partially collapse the bellows40 of the medicament reservoir 14. The partially collapsed bellows 40pressurizes the interior of the reservoir 14 and ensures medicamentdispensed from the dispenser port 44 of the reservoir fills the recess102 of the medicament cup 98 such that a predetermined dose is provided.In the second position, however, the ratchet 106 prevents the cup sled100 from being moved to the delivery passageway 34, such that the recess102 of the medicament cup 98 remains aligned with the dispenser port 44of the reservoir 14 and the pressure relief port 116 of the spacer 38remains sealed by the second sealing surface 124 of the cup assembly 96.

[0061] Upon the cover 28 being fully opened such that the third camsurfaces 94 engage the cam followers 78, the actuator spring 69 isallowed to move the yokes 66, 68 further towards the mouthpiece 24 tothe third position. When moved to the third position, the ratchet 106disengages, or falls below the boss 110 of the cup sled 100 and allowsthe cup sled 100 to be moved by the cup spring 104, such that the filledrecess 102 of the cup 98 is position in the venturi 36 of the deliverypassageway 34 and the dispenser port 44 of the reservoir 14 is sealed bythe first sealing surface 118 of the cup assembly 96. In addition, thepressure relief port 116 is uncovered by the indentation 126 in the sidesurface of the sled 100 to release pressure from the reservoir 14 andallow the bellows 40 to further collapse and accommodate the movement ofthe yokes 66, 68 to the third position. The inhaler 10 is then ready forinhalation by a patient of the dose of medicament placed in the deliverypassageway 34.

[0062] As shown in FIG. 16, a breath-induced air stream 150 divertedthrough the delivery passageway 34 passes through the venturi 36,entrains the medicament and carries the medicament into thede-agglomerator 32 of the inhaler 10. Two other breath-induced airstreams 152 (only one shown) enter the de-agglomerator 32 through thediametrically opposed inlet ports 62 and combine with the medicamententrained air stream 150 from the delivery passageway 34. The combinedflows 154 and entrained dry powder medicament then travel to the outletport 60 of the de-agglomerator and pass through the mouthpiece 24 forpatient inhalation.

[0063] Once inhalation is completed, the mouthpiece cover 28 can beclosed. When the cover 28 is closed, the trigger cams 70 force the yokes66, 68 upwardly such that the first yoke 66 expands the bellows 40, andthe pawl 138 of the second yoke 68 advances the indexing spool 134 ofthe dose counting system 16 to provide a visual indication of a dosehaving been dispensed. In addition, the cup assembly 96 is forced backto the first position by the pusher bar 108 of the upwardly movingsecond yoke 68 (see FIG. 13) such that the boss 110 of the cup sled 100is engaged and retained by the ratchet 106 of the second yoke 68.

[0064] It should be understood that the foregoing detailed descriptionand preferred embodiment are only illustrative of inhalers constructedin accordance with the present disclosure. Various alternatives andmodifications to the presently disclosed inhalers can be devised bythose skilled in the art without departing from the spirit and scope ofthe present disclosure. For example, the medicament cup could beprovided on a rotary sled, advanced by movement of the yokes. Inaddition, the outlet port of the pressure relief could be provided inother locations than the side wall of the slide channel. Furthermore,the dose counting system could be adapted to provide an audibleindications in addition to a visual indication of a dispensed dose.Accordingly, the present disclosure is intended to embrace all suchalternatives and modifications that fall within the spirit and scope ofan inhaler as recited in the appended claims.

What is claimed is:
 1. A medicament inhaler comprising: a mouthpiece forpatient inhalation; a dose meter including a pawl movable along apredetermined path during the metering of a dose of medicament to themouthpiece; a dose counter including, a bobbin, a rotatable spool, arolled ribbon received on the bobbin and rotatable about an axis of thebobbin, the ribbon having indicia thereon successively extending betweena first end of the ribbon secured to the spool and a second end of theribbon positioned on the bobbin, and teeth extending radially outwardlyfrom the spool into the predetermined path of the pawl so that the spoolis rotated by the pawl and the ribbon is advanced onto the spool duringthe metering of a dose.
 2. An inhaler according to claim 1, wherein thespool rotates in a single direction.
 3. An inhaler according to claim 1,wherein the dose counter includes a clutch spring secured to the spooland allowing rotation of the spool in a single direction.
 4. An inhaleraccording to claim 1, wherein the indicia comprises numbers.
 5. Aninhaler according to claim 1, wherein the indicia are provided on aradially outwardly facing surface of the rolled ribbon.
 6. An inhaleraccording to claim 1, wherein the predetermined path of the pawl islinear.
 7. An inhaler according to claim 1, wherein the pawl moves infirst and second directions along the predetermined path and is adaptedto engage the teeth and advance the spool upon movement in the seconddirection.
 8. An inhaler according to claim 1, further comprising ahousing containing the dose counter and include a transparent windowover the indicia of the ribbon.
 9. An inhaler according to claim 1,further comprising a medicament reservoir including a dispensing port,and the dose meter meters a dose of medicament from the dispensing portto the mouthpiece.
 10. An inhaler according to claim 9, wherein thereservoir is adapted to contain dry powdered medicament in bulk form.11. An inhaler according to claim 1, wherein the indicia comprisesnumbers arranged to successively decrease as the ribbon is advanced ontothe spool.